Perylene diimide (PDI) based compounds represent an important class of opto-electronically active materials that are useful in a wide variety of applications, including application as active components in organic solar cells (OSC) [2-4], fluorescent probes in imaging studies [5-7], chemical sensors [8-11], and semiconducting material in organic field effect transistors (OFETs). [12-14] PDI based materials can be synthesized from relatively inexpensive starting materials, and have appreciable and tunable visible light absorption, strong self-assembly characteristics, and low-lying frontier molecular orbitals, that make them useful as electron transport materials in optoelectronic devices. [15-19]
OSC's can provide low-cost, clean energy with minimal environmental impact. [20-22]Fullerenes have been employed as the electron transport material within the active layer of the highest performing OSC devices. [23-27] Soluble PDI based materials are considered as attractive alternatives to fullerenes. [17, 28-33] Functionalized PDI materials exhibit a low lying lowest unoccupied molecular orbital (LUMO) which facilities electron transfer reactions, making them good electron acceptors. Importantly, functionalized PDI derivatives have several advantages over fullerenes, including: low cost, synthetic modularity and increased light absorption in the visible region.
PDI molecules have been functionalized at the imide position with alkyl groups and at the bay position with aromatic units or certain heteroatoms to improve solubility and tailor self-assembly (Formula A) [3,19,34-37]:

For example, dimerization of the PDI chromophore and incorporation of the heteroatoms S or Se in the bay positions of the PDI framework [3,36,37] provided a material having a remarkable effect on both its inter- and intramolecular properties, allowing the fabrication of OSCs with power conversion efficiencies (PCEs) up to 7.1% and 8.4% for the S and Se annulated derivatives, respectively, when paired with tailor-made donor-acceptor type π-conjugated polymers [3,31,32]:

Further derivatization of the dimers of Formula B is limited and large branched alkyl chains are required to ensure adequate organic solvent solubility.
Preferred PDI materials for use as an electron acceptor in OSCs will exhibit high solubility in organic solvents to allow for a diverse array of solution processing protocols to be employed, can be prepared by high yielding and scalable synthetic methods using atom-economical and sustainable chemistry practice, employ modular synthesis allowing for preparation of a library of diverse functionalized materials and maintain the key optical and electronic properties of related PDIs, including strong visible light absorption and deep LUMO energy levels.
Langhalls et al. [39] reported the synthesis of certain PDI materials having a heterocyclic pyrrolic unit installed at the bay position of the chromophore. While these materials were synthesized in good yields, they were not explored as electronically active materials to be self-assembled into superstructures useful for charge transport.
Published US patent application 2017/0352812 published Dec. 7, 2017 relates to certain PDI derivatives of formula:
where X is a halogen, triflyl, tosyl or mesyl group, R1 and R2 are straight-chain or branched alkyl groups and R3 is a straight-chain or branched alkyl group. The application also related to PDI dimers of formula:
where R1-R3 are as defined for the monomer and M is certain divalent linking moieties. The reference also related to certain PDI containing polymers of formula:
where R1-R3 are as defined for the monomer, p is 1 or 0, n is 2, 3 or 4 and M1 is certain divalent, trivalent or tetravalent moieties.
The present invention relates to PDI dimers with active pyrrolic N—H bonds and polymers of such PDIs useful as starting materials for the preparation of additional derivatized PDI dimers and polymers as well as useful as electronically active materials. Derivatized PDI dimers herein could not be readily synthesized by prior art methods.